Open cable set-top box diagnosing system and method thereof

ABSTRACT

An open cable set-top box diagnosing system in which a point of deployment (POD), separated from a main circuit unit, having a newly defined interface is used to check an operation state of an open cable set-top box, transmits the checked state to a predetermined server, according to which the operation state of the open cable set-top box is diagnosed. The open cable set-top box diagnosing system includes an open cable set-top box for checking its own operation state by using a diagnosis resource by a communication protocol between a point of deployment (POD) separated from the main circuit unit and the main circuit, and a head end for providing a service corresponding to a request signal received from the open cable set-top box or providing a broadcast program to the open cable set-top box, and checking the operation state of the open cable set-top box.

This application is a continuation of co-pending application Ser. No.10/919,280, filed on Aug. 17, 2004, which is a continuation ofco-pending application Ser. No. 09/758,417, filed on Jan. 12, 2001, andfor which priority is claimed under 35 U.S.C. §120; and this applicationclaims priority of Application No. 1569/2000 filed in Korea on Jan. 13,2000 under 35 U.S.C. §119; the entire contents of all are herebyincorporated by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to an open cable set-top box of which apoint of deployment (POD) is separated from a main circuit unit, andmore particularly to an open cable set-top box diagnosing system inwhich the POD, separated from a main circuit unit, has a newly definedinterface that is used to check an operation state of an open cableset-top box, transmits the checked state to a predetermined server,according to which the operation state of the open cable set-top box isdiagnosed, and a method thereof.

2. Description of the Background Art

Recently, a digital cable set-top box became popular. The set-top box isconnected to a cable head end through a cable and produces a program fora digital cable. The digital cable set-top box makes a bidirectionalcommunication with the cable head end in a manner that it receives anA/V broadcast program from the cable head end through an inband (IB),and transmits a user's request to the cable head end through an out ofband (OOB) and receives a corresponding service to be displayed.

FIG. 1 is a schematic block diagram showing a construction of aconventional digital cable set-top box. As shown in the drawing, adigital cable set-top box 100 includes a tuner 11 for tuning a receivefrequency to be able to receive an A/V broadcast program correspondingto a frequency of a channel desired by a user from a cable head end (notshown); a QAM (Quadrature Amplitude Modulation) demodulator 12 forreceiving and demodulating an A/V broadcast program tuned by the tuner11; a conditional access unit (CAU) 14 for receiving the demodulatedsignal from the QAM demodulator 12 according to a pre-set condition; aTP (transport) demultiplexer 16 for processing the signal outputted fromthe CAU 14 and outputting a data stream; an MPEG decoder 18-1 and anAC-3 decoder 18-2 for decoding the data stream outputted from the TPdemultiplexer 16 and outputting video signals and audio signals; an OOBprocessing unit 13 for receiving the broadcast program information, suchas a channel tuning or a program guidance from the tuner 11 through theOOB and processing it; and a CPU 17 for receiving the signal processedby the OOB processing unit 13 and controlling the CAU 14 and the TPdemultiplexer 16.

The OOB processing unit 13 includes an OOB receiver 13-1 for receivingthe signal outputted from the tuner 11; an OOB protocol processor 13-3for processing a protocol of the signal processed by the OOB receiver13-1 and outputting it to the CPU 17; and an OOB transmitter 13-2 forprocessing the signal outputted from the OOB protocol processor 13-3 andoutputting it to the tuner 11.

The operation of the digital cable set-top box of the conventional artconstructed as described above will now be explained.

When power is supplied to the digital cable set-top box, the tuner 11receives an A/V broadcast program signal from the cable head end, tunesits frequency so as for a user to receive the A/V broadcast program, andoutputs the tuned A/V broadcast program signal to the QAM demodulator12. Then, the QAM demodulator 12 QAM-demodulates the A/V broadcastprogram signal and the QAM-demodulated signal to the CAU 14.

After the CAU 14 receives the QAM-demodulated signal, in case that theQAM-demodulated signal is in a scrambled state, the CAU 14 descramblesthe QAM-demodulated signal according to a conditional access key (CAK)outputted from the CPU 17 and outputs it to the TP demultiplexer 16.

Then, the TP demultiplexer 16 separates a video packet and an audiopacket of the descrambled signal and outputs them to the video decoder18-1 and the audio decoder 18-2.

The video decoder 18-1 clears an overhead (i.e., various headerinformation or starting code, etc.) from the video packet and performsvariable-length decoding (VLD) for the pure data information. Then, thedecoded information undergoes inverse-quantizing, inverse-discretecosine transforming and motion compensating using a motion vector. Thevideo-signal is restored as a pixel value of the original screen andoutputted to the monitor.

The audio decoder 18-2 decodes the audio packet and outputs it to aspeaker, by using an AC-3 algorithm.

Subscriber managing server systems connected with the cable head endmanages subscribers connected with the cable head end, receivessubscriptions from subscribers who desire to receive a paid programprovided for a paid TV or a pay-per-view and transmits informationcorresponding to the paid program to the subscribers, and manages andoperates the network on the whole.

When the subscriber registers at the subscriber managing server system,he or she is given a password from the subscriber managing serversystem. The paid program is provided from the head end to the set-topbox as the subscriber inputs the password to the set-top box.

The subscriber managing server system renders the head end to transmit adiagnosis command signal to the set-top box 100, thereby diagnosing theoperation state of the subscriber's set-top box. That is, when the OOBreceiver of the set-top box receives the diagnosis command signal fromthe head end, the set-top box performs its own self-diagnosis program todiagnose whether there is an error in each circuit unit of the set-topbox and transmits the diagnosis result to the head end through the OOBtransmitter.

Upon receipt of the diagnosis result of the set-top box, the head endtransmits the diagnosis result to the subscriber managing server systemand receives an instruction from the subscriber managing server systemas necessary.

Since the communication standard is already set, the set-top box ismanufactured by a set-top box manufacturers in cooperation with a cablesystem operator (SO). Accordingly, the cable SOs install the set-top boxonly for the subscribers who order it. Thus, problems arise that it isdifficult to control production of the set-top box, there is a problemof an inventory burden, and the set-top box is to be replaced wheneverthe function of the set-top box is upgraded.

In order to solve the problems, the cable SOs set a standard, such as an‘open cable’, for separating the CAU from the main circuit unit andmanufactures a set-top box without the CAU.

In detail, the open cable set-top box of the above description ismanufactured in a manner that the point of deployment (POD) includingthe CAU that has been installed in the cable set-top box is separatedfrom the main circuit unit of the set-top box. A standard interfaceprotocol between the main circuit unit of the set-top box and the POD isdefined, and an interface is included between the main circuit unit andthe POD.

Accordingly, the set-top box manufacturer can manufacture the open cableset-top box without a restriction, and users also can purchase the opencable set-top box without a restriction.

Accordingly, the users may purchase the open cable set-top box and thePOD provided by the cable SOs and connect them, thereby viewing cablebroadcasting.

FIG. 2 is a schematic block diagram showing a construction of an opencable set-top box in accordance with the conventional art, whichincludes a main circuit unit 200, a point of deployment (POD) module 300and an interface 201 for connecting the main circuit unit 200 and thePOD module 300.

The main circuit unit 200 includes a tuner 21 for tuning a receivefrequency to be able to receive an A/V broadcast program correspondingto a frequency of a channel desired by a user from a cable head end (notshown); a QAM (Quadrature Amplitude Modulation) demodulator 22 forreceiving an A/V broadcast program tuned by the tuner 11, demodulatingit and outputting the demodulated QAM signal through the interface 201to the POD module 300; a TP (transport) demultiplexer 24 for processingthe signal received through the interface 201 from the POD module 300and outputting a data stream; an MPEG decoder 26-1 and an AC-3 decoder26-2 for decoding the data stream outputted from the TP demultiplexer 24and outputting video signals and audio signals; an OOB receiver 23-1 forreceiving the broadcast program information such as a channel tuning ora program guidance from the tuner 21 through the OOB, processing andoutputting it through the interface 201 to the POD module 300; an OOBtransmitter 23-2 for receiving the signal through the interface 201 fromthe POD module 300 and outputting it through the OOB to the tuner 21;and a CPU 25 for controlling each circuit unit of the main circuit unit200 and communicating with the POD module 300 through the interface 201.

The POD 300 includes a local CPU 34 for communicating with the CPU 25 ofthe main circuit unit 200 and controlling the whole POD; a CAU 33 forreceiving the demodulated QAM from the QAM demodulator 22 of the maincircuit unit 200, and descrambling the QAM-demodulated signal accordingto a conditional access key (CAK) outputted from the CPU 34 andoutputting it to the TP demultiplexer 24 in case that theQAM-demodulated signal is in a scrambled state; an OOB protocolprocessor 31 for communicating with the OOB receiver 23-1 and the OOBtransmitter 23-2 under the control of the CPU 34; and a TP demultiplexer32 for receiving the demodulated QAM and the signal from the OOBprotocol processor 31 and demultiplexing them.

The POD module 300 shown in FIG. 2 is in the form of a PCMCIA card.

The operation of the conventional open cable set-top box constructed asdescribed above will now be explained.

When power is supplied to the open cable set-top box, an A/V broadcastprogram is inputted to the POD module 300 through the tuner 21 and theQAM demodulator 22, and the CAU 33 of the POD module 300 descrambles andoutputs the A/V program to the TP demultiplexer 24 of the main circuitunit 200. In other words, the CPU 34 of the POD module 300 interpretsthe command received from the head end through the OOB transmitter 23-2and OOB receiver 23-1 of the main circuit unit 200 and the OOB protocolprocessor 31 and the TP demultiplexer 32 of the POD module 300 andoutputs the interpreted command through a data channel and an extendedchannel of the interface 201 to the CPU 25 of the main circuit unit 200,so that the CPU 25 performs the command instructed by the head end.

Alternatively, the CPU 34 of the POD module 300 transmits a request of auser through the OOB transmitter 23-2 and the OOB receiver 23-1 of themain circuit unit 200 and the OOB protocol processor 31 and the TPdemultiplexer 32 of the POD module 300 to the head end, so that the usermay receive his or her desired program.

FIG. 3 shows a communication protocol between the CPU of the POD and theCPU of the main circuit unit transmitted via the data channel. As shownin the drawing, the communication protocol includes, from the bottom, aPC card physical layer, a PC card link layer, a PC card transportsublayer, a generic transport sublayer and a session layer, which arecommon with other communication protocol, and a resource layer which hasdifferent contents. The resource layer gives and takes a software modulesuch as an object to and from other layers to support execution ofapplications arranged at the upper portion of the resource layer.

The application performs the communication between the POD module 300and the main circuit unit, 200 using resources included in the resourcelayer. Thus, whether the function of the POD interface can be extendedis determined depending on how the resources are defined.

For example, the below Table 1 shows kinds of resources defined in thecurrent U.S. open cable standard. TABLE 1 Resource DVS064 Part B OpenCable Resource Manager Yes Yes MMI Yes Yes Application information YesUpdated Low Speed Communication Yes Updated Conditional Access SupportYes Yes Smart Cart Reader Optional Optional Copy Protection No Yes HostControl-info. Resource Yes Updated Extended Channel Support No YesGeneric IPPV Support No Yes Specific Application Support No Yes

As shown in Table 1, the resources are defined only to supportapplications used by users without including any resources to diagnose adefective state or a defective condition of the set-top box.

Thus, because the open cable set-top box being on the market does notinclude such a resource having a diagnostic function in the PODinterface, it is not possible for the POD module 300 to diagnose itselfor the main circuit unit 200 to determine whether or not the set-top boxis out of order.

In addition, in case that the open cable set-top box is out of order andthus the user is not able to view a desired broadcast program, since theuser has no idea of which one of the POD module and the main circuitunit of the set-top box has been rendered inoperable the user cannotdetermine whether to report he problem to one of the cable SO or theset-top box manufacturer.

Therefore, since the head end, which provides the service to the opencable set-top box, is unable to recognize the disorder of the subscriberset-top box in advance, its competitive edge is degraded with respect tothe satellite broadcast producers and ground wave broadcast producers.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide an opencable set-top box diagnosing system in which a diagnosis resource forchecking an operation state of a set-top box is added to resourcesdefined for POD interfacing so that a cable head end can diagnose theoperation state of a set-top box through a POD, and its method.

Another object of the present invention is to provide an open cableset-top box diagnosing system in which, when a set-top box gets out oforder, diagnosis information on the defective set-top box is transmittedto a set-top box manufacturer on a real time basis through a network, sothat the troubled set-top box can be easily settled, and its method.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described herein,there is provided an open cable set-top box diagnosing system in which acable head end checks an operation state of a set-top box through apoint of deployment (POD) by using a diagnosis resource for checking anoperation state of the set-top box of a resource layer defined forinterface between the point of deployment and the set-top box in an opencable set-top box of which the POD and the set-top box are separated,and the cable head end is connected with a manufacturer of the set-topbox by bidirectional network.

To achieve the above objects, there is also provided an open cableset-top box diagnosing system including an open cable set-top box 400Bfor checking its own operation state by using a diagnosis resource by acommunication protocol between a point of deployment (POD) separatedfrom the main circuit unit and the main circuit, and a head end 400A forproviding a service corresponding to a request signal received from theopen cable set-top box 400B or providing a broadcast program to the opencable set-top box, and checking the operation state of the open cableset-top box.

To achieve the above objects, there is also provided an open cableset-top box diagnosing method including a step in which when a commandfor checking the operation state of the set-top box is inputted from thehead end, the point of deployment (POD) requests system stateinformation from the set-top box, and when the system state informationis received from the set-top box, the POD transmits it to the head end;a step in which the head end checks whether there is an error in theset-top box on the basis of the received system state information andrequests detailed information on a defective sub-system from the POD incase that there is an error in the set-top box; and a step in which thePOD requests detailed information of the defective sub-system from theset-top box, and when detailed information on the defective sub-systemis received from the set-top box, the POD transmits the detailedinformation to the head end.

To achieve the above objects, there is also provided an open cableset-top box diagnosing method including the steps of: requesting stateinformation on the open cable set-top box according to the command forchecking the operation state of the open cable set-top box received fromthe head end; diagnosing whether there is an error in the open cableset-top box on the basis of the state information; and requestingdetailed information on circuit units of a defective open cable set-topbox in case that there is an error in the open cable set-top box.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 is a schematic block diagram showing a construction of a generaldigital cable set-top box;

FIG. 2 is a schematic block diagram showing a construction of an opencable set-top box in accordance with a conventional art;

FIG. 3 illustrates a communication protocol between a POD and a maincircuit unit in accordance with the conventional art;

FIG. 4 is a schematic block diagram showing a construction of an opencable set-top box diagnosing system in accordance with the presentinvention;

FIG. 5 shows an example of coding of a Diag_open_req( ) object;

FIG. 6A shows an example of coding of Diag_open_cnf( ) object;

FIGS. 6B and 6C show Datatype_id value, length and Sub-system_idpreviously defined in the Diag_open_cnf( ) object;

FIG. 7 shows an example of coding of a Diag_sta_req( ) object;

FIG. 8 shows an example of coding of a Diag_stat_cnf( ) object;

FIG. 9 shows an example of coding of a Diag_stat_req( ) object;

FIG. 10A shows an example of coding of a Diag_data_cnf( ) object;

FIG. 10B shows an example of coding of a Diag_data_cnf( ) object; and

FIG. 11 is a flow chart of a method for diagnosing operation state ofthe open cable set-top box in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings.

FIG. 4 is a schematic block diagram showing a construction of an opencable set-top box diagnosing system in accordance with the preferredembodiment of the present invention.

As shown in the drawing, the open cable set-top box diagnostic system ofthe present invention is operable with a head end 400A for providing abroadcast program, subscriber managing servers (S1, S2, . . . , Sn)connected with the head end 400A and an open cable set-top box 400Baccording to the preferred embodiment of the present invention connectedwith the head end 400A.

The open cable set-top box 400B includes a main circuit unit 401, CPU45, a point of deployment (POD) 403 and an interface 402 for connectingthe main circuit unit 401 and the POD 403.

The main circuit unit 401 includes a tuner 41 for tuning a receivedfrequency to receive an A/V broadcast program corresponding to afrequency of a channel desired by a user from a cable head end 400A; aQAM (Quadrature Amplitude Modulation) demodulator 42 for receiving anA/V broadcast program tuned by the tuner 41, demodulating it andoutputting the demodulated QAM signal through the interface 402 to thePOD 403; a TP (transport) demultiplexer 44 for processing the signalreceived through the interface 402 from the POD 403 and outputting adata stream; an MPEG decoder 46-1 and an AC-3 decoder 46-2 for decodingthe data stream outputted from the TP demultiplexer 44 and outputtingvideo signals and audio signals; an OOB receiver 43-1 for receiving thebroadcast program information, such as a channel tuning or a programguidance from the tuner 41 through the OOB, processing and outputting itthrough the interface 402 to the POD 403; an OOB transmitter 43-2 forreceiving the signal through the interface 402 from the POD 403 andoutputting it through the OOB to the tuner 41; and a CPU 45 forcontrolling each circuit unit of the main circuit unit 401 andcommunicating with the POD 403 through the interface.

According to the preferred embodiment, the POD 403 includes a CPU 54 forcommunicating with the CPU 45 of the main circuit unit 401 andcontrolling the whole POD; a CAU 53 for receiving the demodulated QAMfrom the QAM demodulator 42 of the main circuit unit 401, anddescrambling the QAM-demodulated signal according to a conditionalaccess key (CAK) outputted from the CPU 54 and outputting it to the TPdemultiplexer 44 in case that the QAM-demodulated signal is in ascrambled state; an OOB protocol processor 51 for communicating with theOOB receiver 43-1 and the OOB transmitter 43-2 under the control of theCPU 54; and a TP demultiplexer 52 for receiving the demodulated QAM andthe signal from the OOB protocol processor 51 and demultiplexing them.

Preferably, the POD described above may be in a form of a PCMCIA card orother suitable interface, wherein a communication module of the PCMCIAcard type is connected to the POD interface port.

The operation of the open cable set-top box of the present inventionconstructed as described above will now be explained.

When power is supplied to the open cable set-top box 400B, an A/Vbroadcast program is inputted to the POD 403 through the tuner 41 andthe QAM demodulator 42, and the CAU 53 of the POD 403 descrambles andoutputs the A/V program to the TP demultiplexer 44 of the main circuitunit 401. In other words, the CPU 54 of the POD 403 interprets thecommand received from the head end through the OOB transmitter and OOBreceiver of the main circuit unit 401 and the OOB protocol processor 51and the TP demultiplexer 52 of the POD 403 and outputs the interpretedcommand through a data channel and an extended channel of the interface402 to the CPU 45 of the main circuit unit 401, so that the CPU 45performs the command instructed by the head end 400A.

Alternatively, the CPU 54 of the POD 403 transmits a request of a userthrough the OOB transmitter 43-2 and the OOB receiver 43-1 of the maincircuit unit 401 and the OOB protocol processor and the TP demultiplexer52 of the POD 403 to the head end 400A, so that the user may receive thedesired program.

As described earlier, FIG. 3 illustrates the communication protocolbetween the CPU 54 of the POD 403 and the CPU 45 of the main circuitunit 401 transmitted via the data channel of a conventional open cableset-top box, and includes, from the bottom, a PC card physical layer, aPC card link layer, a PC card transport sublayer, a generic transportsublayer and a session layer, and a resource layer.

In contrast to the conventional devices, the resource layer of thepresent invention also includes a resource for diagnosing the operationstate of the set-top box, so that the set-top box can diagnose its ownoperation state. Also, the resource layer contains a resource managerresource, an MMI resource, an application information resource, a lowspeed communication resource, a conditional access support resource, acopy protection resource, a host control information resource, anextended channel support resource, a generic IPPV support resource, aspecific application support resource and a diagnostic resource. Whereinthe diagnostic resource of the POD includes at least one diagnosticstate request object and a diagnostic state confirmation object. Thediagnostic state request object performs a diagnosing of a system andthe diagnostic state confirmation object transfers the system state, ordiagnosis result to the head end 400A or the broadcasting station.

In addition, the diagnostic resource contains a diagnostic open requestobject, a diagnostic confirmation request object, a diagnostic staterequest object, a diagnostic state confirmation object, a diagnosticdata request object, and a diagnostic data confirmation request. Thediagnostic confirmation object transfers the diagnosis result performedby the OOB protocol processor 51 to the head end 400A or to thebroadcasting station.

In other words, by adding a diagnosis resource for checking theoperation state of the set-top box to the resources defined for the PODinterface, the cable head end is able to check the operation state ofthe set-top box through the POD module, so that the cable SOs can manageand administer the subscriber set-top box, and can recognize a necessaryremedial step in advance and quickly fix the problem.

Accordingly, in case that the set-top box has an error, the cable headend 400A informs a corresponding set-top box manufacturer of the errorinformation on the defective set-top box on a substantially real timebasis through a network, so that it can be repaired or replaced rapidly.That is, the head end periodically checks an operation state of theset-top box and informs a pertinent set-top box manufacturer ofdiagnosed information on the set-top box with a problem through thenetwork on the real time basis.

The diagnosis resource of the present invention which is added to theconventional resource layer of the POD interface is described in detail.

The diagnosis resource preferably includes defined objects to exchangediagnosis data between the POD 403 and the main circuit unit 401. Theobjects determine a specific ID information data format to discriminatesubscriber set-top box, such as a manufacturer name, a model name or aserial number, divides the whole system to sub-systems, a functionalunit to be checked, and gives an ID, and defines states of eachsub-system. That is, the diagnostic resource previously defines anobject that the POD interface module and the set-top box are to use forexchanging the diagnosis data, determines a specific ID information dataformat for identifying the subscriber set-top box, divides the wholesystem into sub-systems, the functional unit for checking, assigns theID to each sub-system, defines each state of the sub-systems andexchanges status information of each sub system as a data of the object.

For example, the objects belonging to the diagnosis resource of thepresent invention are as follows.

Diag_open_req( ) POD→set-top box: requesting to open diagnosis source

Diag_open_cnf( ) POD←set-top box: replying for sub-system constructioninformation of the set-top box

Diag_state_req( ) POD→set-top box: requesting a system state

Diag_state_cnf( ) POD← set-top box: replying whether there is an errorin the system

Diag_data_req( ) POD→set-top box: requesting detailed information incase that there is an error in the system

Diag_data_cnf( ) POD⇄set-top box: replying to the defective sub-systemstate

FIGS. 5 through 10 illustrate examples of codings to implement theobjectives describe above.

FIG. 5 shows an example of coding of a Diag_open_req( ) object; FIG. 6Ashows an example of coding of Diag_open_cnf( ) object; FIGS. 6B and 6Cshow Datatype_id value, length and Sub-system_id previously defined inthe Diag_open_cnf( ) object; FIG. 7 shows an example of coding of aDiag_sta_req( ) object; FIG. 8 shows an example of coding of aDiag_stat_cnf( ) object; FIG. 9 shows an example of coding of aDiag_stat_req( ) object; FIG. 10A shows an example of coding of aDiag_data_cnf( ) object; and FIG. 10B shows an example of coding of aDiag_data_cnf( ) object.

FIG. 11 is a flow chart of a method for diagnosing operation state ofthe open cable set-top box in accordance with the present invention.

With reference to FIG. 11, after the OOB transmitter 43-2 and receiver43-1 of the main circuit unit 401 connected with the head end 400Ainterpret the command received from the head end, the CPU 54 of the POD403 renders the OOB transmitter 43-2 and receiver 43-1 to communicatewith the CPU 45 of the main circuit unit 401 through the data channel ofthe extended channel through the interface 402 to perform the commandinstructed by the head end, or transmits contents inputted by the userand the state information of each circuit unit of the set-top boxthrough the OOB transmitter and receiver of the main circuit unit 401connected with the head end.

When the cable head end 400A requests various ID information related tothe set-top box and the information on the sub-system or componentconstruction from the POD (step 1), the POD requests the main circuitunit of the set-top box to open the diagnosis resource by using theDiag_open_req( ) object as shown in FIG. 5 (step 2).

Then, the main circuit unit transmits the information requested by thePOD obtained on the basis of the pre-set input information by using theDiag_open_cnf( ) object as shown in FIG. 6 (step 3).

Accordingly, the POD transmits the various ID information related to theset-top box and information on the sub-system construction to the cablehead end (step 4).

Thereafter, when the cable head end transmits the command forperiodically checking and reporting the operation state of the set-topbox to the POD (step 5), the POD checks the operation state of theset-top box through the diagnosis resource defined in the POD interfaceand reports it to the cable head end.

That is, the POD requests the system state from the set-top box by usingthe Diag_stat_req( ) object as shown in FIG. 7 (step 6), the maincircuit unit of the set-top box, which has periodically checked theoperation state of the set-top box, transmits the system state of theset-top box to the POD by using the Diag_stat_cnf( ) object as shown inFIG. 8 (step 7).

Then, the POD transmits the system state of the set-top box to the cablehead end (step 8), and the cable head end checks whether there is anerror in the system on the basis of the received information (step 9).

In case that there is no error in the system of the set-top box, thecable head end repeatedly checks the operation state of the set-top box(steps 5, 6, 7, 8 and 9), while, in case that there is an error in thesystem, the cable head end requests detailed state information on thedefective sub-system from the POD (step 10).

Then, the POD requests detailed information on the sub-system of thedefective set-top box from the main circuit unit of the set-top box byusing the Diag_data_req( ) object as shown in FIG. 9 (step 11).

Then, the main circuit unit of the set-top box transmits the stateinformation of the sub-system of the defective set-top box to the POD byusing the Diag_data_cnf( ) object as shown in FIG. 10 (step 12), and thePOD transmits the received state information of the sub-system of theset-top box to the cable head end (step 13).

While the head end is checking the operation state of the set-top box,in case that the head end is informed of the defective set-top box fromthe POD, the head end registers the informed content with the subscribermanaging servers (S1, S2, . . . , Sn) and informs the correspondingmanufacturer of the defective set-top box of the ID of the defectiveset-top box and the abnormal operation state content on the real timebasis.

Accordingly, various service (i.e., early report on a trouble, repairingor replacing, etc) for the troubled set-top box can be effectively andquickly provided by the manufacturers.

In addition, the cable head end is able to detect the trouble of the PODas it occurs and the cable head end reports the error to an A/S serviceperson of the cable head end itself, so that its own A/S service personcan expeditiously settle the problem.

As described, in the open cable set-top box diagnosing system and methodaccording to the preferred embodiment of the present invention, theinterface for diagnosing the set-top box function is added to the PODinterface of the digital cable set-top for an open cable, so that thecable head end can manage the ID information to discriminate set-topboxes owned by each subscriber and the operation state information ofeach set-top box on the real time basis.

In addition, in case that the set-top box or the POD is improperlyoperating the diagnosis information on the troubled set-top box may betransmitted to the corresponding set-top box manufacturer, so that thetroubled set-top box or the POD can be quickly repaired or replaced.

As the present invention may be embodied in several forms withoutdeparting from the spirit or essential characteristics thereof, itshould also be understood that the above-described embodiments are notlimited by any of the details of the foregoing description, unlessotherwise specified, but rather should be construed broadly within itsspirit and scope as defined in the appended claims, and therefore allchanges and modifications that fall within the meets and bounds of theclaims, or equivalence of such meets and bounds are therefore intendedto be embraced by the appended claims.

1. A method of interfacing with a host device receiving a broadcastingsignal, the method comprising: descrambling a scrambled broadcastingsignal and transmitting the descrambled signal to the host device;sending a diagnostic request to the host device to perform a specificset of diagnostic functions by using a diagnostic resource; andreceiving a diagnostic response including a diagnostic result of theperformed diagnostic functions from the host device by using thediagnostic resource, wherein the diagnostic request is defined in adiagnostic request object and the diagnostic result is defined in adiagnostic confirmation object, and wherein the diagnostic requestobject and diagnostic confirmation object are defined by the diagnosticresource.
 2. The method of claim 1, wherein the diagnostic resultincludes an operation status of at least one sub-system included in thehost device.
 3. The method of claim 1, wherein the diagnostic request issent to the host device in a data channel.
 4. The method of claim 1,wherein the diagnostic response is received from to the host device in adata channel.